Simulated gene therapyApril 30, 2009In a recent issue of The Journal of Chemical Physics, published by the American Institute of Physics (AIP), a group of researchers at the University of California, Berkeley and Los Alamos National Laboratory describe the first comprehensive, molecular-level numerical study of gene therapy. Their work should help scientists design new experimental gene therapies and possibly solve some of the problems associated with this promising technique. "There are several barriers to gene delivery," says Nikolaos Voulgarakis of Berkeley, the lead author on the paper. "The genetic material must be protected during transit to a cell, it must pass into a cell, it must survive the cell's defense mechanisms, and it must enter into the cell's guarded nucleus." If all of these barriers can be overcome, gene therapy would be a valuable technique with profound clinical implications. It has the potential to correct a number of human diseases that result from specific genes in a person's DNA makeup not functioning properly -- or at all. Gene therapy would provide a mechanism to replace these specific genes, swapping out the bad for the good. If doctors could safely do this, they could treat or even cure diseases like cystic fibrosis, certain types of cancer, sickle cell anemia, and a number of rare genetic disorders. Safety is a primary concern when working with gene therapy. Some of the first attempts at gene therapy used viruses to insert DNA into cells -- something that viruses naturally do anyway. Viruses can be dangerously toxic, however, and this fact was tragically demonstrated a decade ago when an 18-year-old boy enrolled in a gene therapy study had a massive immune reaction to the viruses used. He died just a few days into the treatment from multiple organ failure, precipitating an immediate halt to the trial. Since then, many alternatives to viruses have emerged for use in gene therapy, including synthetic molecules like "dendrimers," a word that derives from the Greek word for "tree." Similar to trees, dendrimers are branching molecules that are slightly positively charged. This allows them to be loaded with DNA (which is slightly negative charged) for insertion into a cell. Dendrimers seem to offer many advantages over viruses. They may be much less toxic, and they may offer other advantages in terms of cost, ease of production, and the ability to transport very long genes. If they can be designed to efficiently -- and safely -- shuttle genes into human cells, then they may be a more practical solution to gene therapy than viruses. So far, laboratory experiments with different types of dendrimers have shown that they can insert genes into cells, but only with very low efficiency. Hoping to discover the key to improving this efficiency, Voulgarakis and his colleagues simulated the detailed, atomic-level physical process of dendrimers entering cells. They varied parameters like the dendrimer size and the length of the DNA they carry. Modeling these parameters on a computer is a fast, inexpensive approach for testing different ideas and optimizing the delivery vehicle. What they uncovered were the key factors that determine the success of dendrimers as gene delivery vehicles -- things like the charges of the dendrimers and their target cell membranes, the length of DNA, and the concentration of surrounding salt. Their work has illuminated some of the molecular-level details that should help clinicians design the most appropriate gene vectors. "Our study indicates that, over a broad range of biological conditions, the dendrimer/nucleic acid package will be stable enough to remain on the surface of the cell until translocation," says Voulgarakis. Dendrimers are also used clinically for delivering cancer drugs to tumors, and for helping to image the human body. In the future, Voulgarakis and his colleagues plan to study the possibility of using dendrimers as drug delivery vehicles. American Institute of Physics |
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| Related Gene Therapy Current Events and Gene Therapy News Articles Immune therapy can protect against or treat later lymphoma Specially developed immune system cells that target the common Epstein-Barr virus can protect immune-suppressed bone marrow transplant recipients against lymph system disease and cancers that arise from the viral infection. Caltech researchers show efficacy of gene therapy in mouse models of Huntington's disease Researchers at the California Institute of Technology (Caltech) have shown that a highly specific intrabody (an antibody fragment that works against a target inside a cell) is capable of stalling the development of Huntington's disease in a variety of mouse models. Immunotherapy demonstrates long-term success in treating lymphoma Targeted immunotherapy has been an attractive new therapeutic area for a number of cancers because it has the potential to destroy tumor cells without damaging surrounding normal tissue. New study results demonstrate high success rates using specialized white blood cells to prevent or treat lymphoma associated with the Epstein-Barr virus (EBV-lymphoma) in patients who have received a hematopoietic stem cell transplant (HSCT). Toward bold new anti-cancer medicines Bold new strategies in the battle against cancer may turn forms of the disease that presently are incurable into manageable conditions that can be controlled for long periods of time. 1 shot of gene therapy and children with congenital blindness can now see Born with a retinal disease that made him legally blind, and would eventually leave him totally sightless, the nine-year-old boy used to sit in the back of the classroom, relying on the large print on an electronic screen and assisted by teacher aides. Master regulator found for regenerating nerve fibers in live animals Researchers at Children's Hospital Boston report that an enzyme known as Mst3b, previously identified in their lab, is essential for regenerating damaged axons (nerve fibers) in a live animal model, in both the peripheral and central nervous systems. Governor recognizes stem cell research at Einstein Albert Einstein College of Medicine of Yeshiva University hosted a roundtable discussion on stem cell research with New York Governor David A. Paterson today. Michigan hospital launches gene therapy study for Parkinson's disease A Michigan hospital is embarking on a research study for advanced Parkinson's disease using a state-of-the-art treatment called gene transfer. Historic gene therapy trial to treat Alzheimer's disease underway at Georgetown Researchers in the Memory Disorders Program at Georgetown University Medical Center are now recruiting volunteers for a national gene therapy trial - the first study of its kind for the treatment of patients with dementia due to Alzheimer's disease. University of Iowa scientists use blood-brain barrier as therapy delivery system The blood brain barrier is generally considered an obstacle to delivering therapies from the bloodstream to the brain. However, University of Iowa researchers have discovered a way to turn the blood vessels surrounding brain cells into a production and delivery system for getting therapeutic molecules directly into brain cells. More Gene Therapy Current Events and Gene Therapy News Articles |
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